Electronic counting device



Feb. 5, 1952 R. E. MUMMA ELECTRONIC COUNTING DEVICE Filed July 10, 1947 d 2.35 cozosuzou 2 2 5 0350 o 2:: E 52323 2 2 520350 62: *0 52.280 E2328 2 3230 x x XX FXX IOXX

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Zmventor ROBERT E. MUMMA HIS (Iflorneg A VV Patented Feb. 5, 1952 ELECTRONIC COUNTING DEVICE Robert E. Mumma, Dayton, Ohio, assignor to The National Cash Register Company,

Dayton,

Ohio, a corporation of Maryland Application July 10, 1947, Serial No. 759,922

6 Claims.

This invention relates to electron tube numerical accumulators and in particular relates to a novel circuit arrangement in which each denomination of the accumulator is made up of four, cascaded trigger-pairs of tubes which are so controlled as to be capable of accumulating data in the decimal notation.

The principal object of this invention is to provide a novel accumulator of data in the decimal notation using four cascaded electronic devices for each decimal denomination.

A further object of the invention is to control a four denominational binary counter in a novel way toenable it to operate as a single denomination of a decimal counter.

A still further object of the invention is to control a four denominational binary counter to cause an additional entry to be made in the 2 denomination thereof each time certain entries are made in higher denominations, thereby enabling the counter to operate as a single denomination of a decimal counter.

Another object of the invention is to control one of the trigger-pairs of tubes of a cascaded bank of four trigger-pairs of tubes in such a manner that the bank of tubes will return to a given condition of conduction upon the application of ten impulses thereto.

With these and incidental objects in view, the

: inventionincludes certain novel features of con- :7

struction and combinations of parts, the essential elements of which are set forth in appended claims and a preferred form or embodiment of which is'hereinafter described with reference to the drawings which accompany and form a ious trigger-pairs of tubes.

General description A'The numerical accumulator of the invention can contain as many denominational banks of .tubes as are required to make up the desired :capacity;

Since each denominational bank of the accumulator is of the same construction, it is believed that an understanding of, the novel accumulator will be clear from an. explanation of the circuits and operation of one denominational bank and its relation to adjacent banks.

The novel bank is made up of four pairs of tubes, each pair being trigger-connected and the four pairs being connected in cascade. Each pair of tubes which form a trigger-pair, are so interconnected in a circuit and operate in such a. manner that the circuit can assume two conditions of stability, that is when either tube is conducting the other will be at out 01f.

Potential impulses applied to the tubes are effective to change the interconnected tubes from either condition of stability to the other, every other impulse bringing the interconnected pair to a like condition of stability.

For convenience of the explanation of this application the trigger-pairs of tubes will be considered in their on condition when tubes A, B.

I C and D (Fig. 1) are conducting and will be considered in their oil condition when these tubes are non-conducting.

The four trigger-pairs tubes A and A, B and B, C and C and D and D are connected in cascade, or series. and input impulses are applied to the first trigger-pair, tubes A and A, of the series to cause this trigger-pair to assume a1- ternately its on and its off conditions. The series connection between the first and second trigger-pairs is effective to transmit an impulse, which is generated when the first trigger-pair returns to its oil condition, to the second trigger-pair, tubes B and B, to cause a change in the condition of stability of that pair.

In a similar manner the second and third trigger-pairs generate impulses as they returnto their ofi condition and these impulses are transmitted to the third and fourth trigger-pairs, respectively, over the series connections, to cause changes in the condition of stability therein.

In addition to the above circuits, there are further connections between the third and fourth trigger-pairs and the second trigger-pair which are effective to cause the second trigger-pair to assume its on condition each time the third or fourth trigger-pair of tubes assumes its on position.

These series connections and further connections enable the four trigger-pairs to be restored to any previous setting when ten impulses have been applied to the bank and enable the triggerpairs, by their on and off conditions, in combination, to represent the digits 1 to 9 and 0.

The impulse, which when applied to the bank causes it to exceed its capacity, causes the fourth trigger-pair to return to off condition as will 3 be explained hereinafter, and the return of this pair to off condition will generate an impulse which can be applied to the input of the next higher denomination to cause an entry of a unit therein.

The tubes of the bank may be restored to zero representing condition by causing all of the trig ger-pairs of the bank to assume their of? condition.

Any suitable indicating means may be used to.

indicate the value standing on the accumulator. One such indicating means may take the form of a suitable indicator lamp for. each trigger-pair, which lamp will glow when its related triggerpair is on on condition. The value of an amount standing on the bank at any time can readily be determined from the lamp or lamps,

which are glowing, according to the combinations shown in the chart, Fig. 2.

Normally sixteen impulses would be required to cause a bank of four cascaded trigger-pairs to exceed its capacity and return to its original setting. As indicated above, however, the novel bank of four cascaded trigger-pairs can be made to exceed its capacity and return to its original setting by the application of only ten impulses thereto.

The manner in which this is accomplished may best be understood by considering each of the four. trigger-pairs of tubes as a denomination of: abinary. counter, the pair of tubes A and A." representing-the 2 denomination, tubes B and B representing the 2 denomination, tubes G and Ci-repres'enting the 2. denomination, and

tubes'D and D7 representing 2 denomination,

and by considering the on condition of the trigger-pair ofitubesas indicating a value standing in that order. The normal series connections between the trigger-pairs. cause an operation-of a higher order pair for every two opera- 11 tions of: alower, order pair and this would mean that. they four; orders, would return to, starting condition only after, sixteenimpulses, were, imp ssed on the, 'cs ri er-v connections, which are provided between the triggerrpairs of the 2? and 2 denominations and thetrigger-pair of the 2, denomination areeifective to causethe 2 denomination to receive an extraentry. or assume an on condition each time one of the higher order trigger-pairs assumes an fon condition. This extra entry into the 2 order will occur three times during the entry-of ten impulses and will have the same effect as; though six additional impulses were applied to the counter. This automatic entry of the value of 6 enables the four orders to returnto starting condition, after only ten impulses are impressed on the counter.

Therfour, cascaded trigger-pairstherefore are capable of operating as a single denomination.

of a decimal accumulator and can, by, the combihatioris or their conducting tubes, represent any 'ofthe digits 1 to 9 inclusive and 0."

Circuits Fig. 1 shows a circuit diagram of a representative bank of tubes connected to operate accord- [rig to the invention to enable four cascadedtrigger-pairs of tubes to accumulate andre'present values in the decimal notation.

This bank of tubes is merely illustrative of the invention and it is not intended that; the invention be limited to the use of the particular potentials and the values of" resistance and capacitance given in the followingdescription be- However, the circuit cause the potentials applied to the various elements of the tubes are merely selected as convenlent potentials for the disclosure, and the circuit elements of resistance and capacitance correspond in relative value to the potentials chosen. It is obvious that other potentials may be used and the values of the circuit elements adjusted accordingly to maintain the proper relation between the various parts of the circuit. All potentials given herein are with reference to ground.

In Fig. 1, the tubes of each trigger-pair are shown as the elements of a dual triode, such as a commercial 6J6 type of tube, but it will be obvious that as faras the invention is concerned other types of tubes may be used andeach of the tubes of a trigger-pair of tubes may occupy a, separate envelope.

Various types of circuits for connecting tubes to operate as trigger-pairs are well known and the. one chosen to illustrate, the invention enables the. trigger-pair to change from on" to off" condition, and vice versa, upon the application negative input impulses to the control grids.

If other typesof trigger-pairs'are used, suitable-circuit changes to accommodate. the type of trigger-pair used can be made without departing fromthe invention.

Thecircuitsfor each of the trig cr-pairsare substantially the same, and their operation will be clear from anexplanation of the circuits by which the tubes A, and A (Fig. l) are connected to operate asa trigger-pair.

The anodes of tubes A and A are-connected over resistors, as 50, each of 47,000 ohms, to an anode potentialsupply conductor 5! which is in turn connected to terminal 52 to which is applied a positive potential of 260 volts from anysuitable source of potential supply.

The common cathodev of the tubes A and A is connected directly toground. v

The control grids for. the tubes A andA' are connected over resistors, as 53, each of 120,000 ohms, ,to a negative potential supply; conductor 54 which is in turnv connected to terminal 55 to which is, applied a negative biasing potential of 7 5 volts from any suitablesource of potential supply. The control grid'for tube A is also connectedto the. anode of tube A over a resistor, as 56, of 200,0 00 ohmsin parallel with acapacitor, as 5.1; of 500micro-microfarads, which connection oiv the control grid of tube Alto the anode of tube A5 enables the conduction or non-conducimpulses, to cause entries to be made in the denomination.

The operation ofthe trigger-pair is as follows. Consider the pair as in its on condition with tube A conducting and tube A non-conducting. When tube A is conducting its :anode, due to the 7 potential drop across resistor 50 will be lesspositiv'e than when the tube: is non-conducting, and

a this condition is conveyed, through the coupling I,- between the anode'of tube-A and control grid 'oi ofi condition to its "on" condition.

tube A to the grid of tube A to bias tubeA' to cut-off. Tube A being non-conductinghas its anode potential more positive, which condition is conveyed to the control grid of tube A-to keep this tube conducting. A negative impulse applied to the two grids will be inelfective on the grid of tube A which is already biased to out off,

L grid of tube A and causes the tube A to begin to'conduct. The drop in anode potential'of tube A is applied to the control grid of tube A to keep this tube biased to cut-off. In this manner the tion. The next impulse on this pair will operate in a similar manner to changethe pair from its The input conductor 62 for the second triggerpair, tubes B and B, is connected to the anode of tube A and has a negative impulse impressed thereon each time tube A becomes conducting, that is, each time the first trigger-pair assumes .its "ofi condition. The second trigger-pair therefore receives an entry for every two entries .made in the first trigger-pair. The non-conducting tube of the second trigger-pair has sufiicient negative bias that the rise inpotential which occurs at the anode of tube A when the nected to the anode of tube B and has a negative impulse impressed thereoneach time the second the input conductor 63 trigger-pair returns to its ofi condition. The

third trigger-pair also is not afiected by the 1 turning .of the second triggerepair to its "on condition.

Likewise the input conductor 64 for the fourth and final trigger pair of the bank, tubes D' and D,

is connected to the anode of tube C' and has a 7 negative impulse impressed thereon each time the third trigger-pair returns to its off condition. The fourth trigger-pair also is not afiected by the turning of the third trigger-pair to its on condition.

The anode of tube C of the third trigger-pair is coupled over a rectifier 6'5 and resistor 66 of 5 megohms in parallel, and a capacitor 61 of 100 micro-microfarads to the grid of tube B of the second trigger-pair. This coupling enables' the turning on? of the third trigger-pair to provide a negative impulse which turns the second trigger-pair on.

The second trigger-pair is Withfurther reference to the chart, Fig. -2 ,it will be noted that the tube D of the fourthtrigger-pair of the bank changes from a conducting to a non-conducting condition only as the representation of the bank passesfrom "9 to"0."' This means that the other tube of the pair, tube 'D, becomes conducting'at this time: A connection from the anode of tube'D over conductor "15 and rectifier 16 and resistor "ll in parallel, ex- .tends to the input conductor of the next higher denomination to transmit the negative impulse.

generated when tube D becomes conducting, to

the next higher denomination to cause a" tens carry entry of a unit to be made thereineach time the "lower order exceeds its capacity and passes from a representation of "9" to a representation of 0.

' When a plurality of banks'similar to the bank of Fig. 1v are used to form a multi-denominational accumulator, digit entries in the several orders should be made in succession to avoid the entry of tens transfer values during digit entries.

In order to indicatewhich of the trigger-pairs is in on condition-.that is, which'of thetubes A, B, C and D is conducting-glow tubes; as tube 18, are connected across the anode resistors for tubes A, B, C and D and will glow when these tubes are conducting. By checking the glowing tubes with the chart, Fig. 2, the'value standing on the bank can readily be ascertained. v j

When it is desired to restore the bank to "its zero representing condition switches S-l,' S92, S-.-3 and 3-4 are momentarily closed simultaneously. These switches connect the grids of the tubes A, B, C and D' to ground, causing these tubes to become conducting, if they are not already conducting. Conduction in tubes A, B,

C and D will, through the trigger connections, cause tubes A, B, C and D to be cut off, which is the condition representative of zero.

Operation In order to prepare the novel accumulator bank for operation, the switches S.-l, S4, S74 and 5-4 are momentarily closed to connect the grids pf the tubes A, B, C and D to ground causing these tubes. to become conducting, and, due to the trigger. connections, causing thetubes A,-.B,,C

and D to become non-conducting. This is the 01f condition of the various trigger-pairs and -is the. condition of the bank which represents ,The first impulse which is applied to the bank in this zero representing condition causesthe first trigger-pair to assume an "on" condition with tube A conducting and tube A non-conducting. As tube A becomes non-conducting, its

turned on in this manner when the digits 4 and 8 are to be represented by the bank as The anode of tube D of the fourth trigger-pair 6 the first impulse, tube A is conducting and'tubes is also coupled to the control grid of tube 13 of second trigger-pair over a rectifier 'HJ and resistance ll of 5 megohms in parallel, a capacitor turned on. The second trigger-pair is turned "on by the fourth trigger-pair when the bank is ito indicate the digit 6,.as is clearly shown inthe chart, Fig. 2.

anode potential rises and forms a positive impulse. This positive impulse is applied to the tubes B and B of the next trigger-pair but is ineffective tochange the conducting condition To! the tubes because it is ineffective to overcomethe bias of the grid of tube B and has no appreciable efiect on the grid of tube B which is already at its-more positive potential. After the receipt of B, C and D' are non-conducting, which is the condition representative of the digit 1.

' 12 of 100 microfarads and conductor 13. This [coupling enables the second trigger-pair to be turned on when the fourth trigger-pair is The next impulse applied to the bank causes thefirsttrigger-pair' to assume its .off" condi' tion. with tube A non-conducting and tube A conducting. The conduction occurring in tube i A causes the anode potential of this tube to become lesspositive, forming a negative impulse which is applied to the control grids of'thetubes .B and'B' ofthenext trigger-pair and causes this pair to assume its on condition with tube. B conducting and tube Bf non-conducting, The positive impulse. caused when conduction ceases in tube B will not affect the conductingand noncondu'ctin'g condition of the tubesC and C' oft-he the first. trigger-pair to assume. its oncondition with tube Aconducting and tube A" non-conducting. This. change will not affect. the conducting v condition of the tubes 13 and B of the next tri ger-pair so that at the end of. this entry tubes A and B will be conducting and tubes .C and D will be non-"conducting, which is the condition representative of the digit 3.

i The fourth impulse applied to the bank causes --the first trigger-pair to returnto its off con-- dition with tubev A non-conducting and tube A conducting. The potential drop of the anode of .tube A, as the first trigger-pair returns to its oiT'condition, forms a negative impulse which is. applied to the tubes B and B of the second trigger-pair, causing the second pair to return to v its 05 condition with tube B non-conducting and tube B conducting. The anode: potential drop of tube B" as the tube becomes conducting causes a negative impulse to be applied to the tubes C and .C. oi the. third trigger-pair to cause this trigger-pair to assume its on condition with tube C conducting and tube C non-conducting. When tube C becomes conductingv its anode drop is conveyed through the circuit including rectifier 65 to tube B which causes tube B to become non-conducting and tube B to become conducting, thereby causing the second triggerpair to return to its on'condition. At the end of this entry, tubesB and C will be conducting and tubes A and D will be non-conducting, which is the condition representative of the digit 4..

The fifth impulse applied to the bank will cause only the first trigger-pair to change, that is tube 'A to become conducting and. tube A to become: non-conducting. At the end of this entry, tubes A, B and C will be conducting and tube Dwill be non-conducting which is the condition representative of the digit 5.

The sixth impulse impressed on the bank. causes the first trigger-pair to return to its off" condition with tube A non-conducting and tube A conducting. The return of the first trigger}- pair tojits on condition causes a negative impulse to be impressed on tubes B and B'- of the second trigger pair causing this pair also to reand tube C conducting. Thereturn ofthe. third trigger-pair to its 011* condition impresses a negative impulse on the tubes D and D .of the f nal trigger-pair causing this pair to assum its "on condition with tube D conducting'andtube D non-conducting. 'When' the final trigger-pair assumes its.on" condition and tube D becomes conducting its anode potential drop is conveyed over the circuit including rectifier 10 to the tube B causing tube B to become non-conducting and, through the trigger connections causing tube B to become conducting therebyca'using the sec endpair to return toits on condition- At the end of. this entry, tubes B and ,D. will be conduc ng and tubes .A and C will be non-condu ting which is the condition representative pf the digit 6.

The seventh impulse applied to the bank will cause. the first triggerepairto assume its on condition with tube A conducting and tu e A noneconducting. There will be no change inthe conducting condition of the other triggerepairs at this time. At the end of this entry, tubesA, B and .D will be conducting '-and,tube C will be non-conducting which is th condition presentativeiof the digit '1,-

The eighth impulse applied to the bank will cause the firs trieservp o eturn to its "Q condition with tube A noneconducting and tube A conducting. As before, the return of the first trigger-pair to ofi condition causes a negative impulse to be applied. to the tubesB and B of the second trigger-pair which causes the second trigger pair also to return to, ofi condition with tube B non-conducting and tubeB' conducting. The return of the second trigger-pair to -ofi" condition sends a negative impulse to the tubes .0 and C. of the third trigger-pair which causes this pairto assume an. onfcondition with tube C'conductingand tube C non-conducting. When the'third' trigger pair assumes its on condition and tube C becomes conducting, its anode potentialdrop is conveyed over the circuitincluding the rectifier to tube B", causing-tube B tobeccme non-conducting, which through the trigger connections causes tube B to become conducting. At the end of this entry tubes B, C and D are conducting and tube A is non-conducting. This is the condition representative of the digit 8;!!- l Theninth impulse will cause the first triggerpair to assume its on condition with tube A conductingand tube A non-conducting. This will cause the conductingcondition of none of the other trigger-pairs to be affacted, At the end of this entry, tubes A, B, C, and D will be conducting, which is the condition representative :of the digit 9.

When the tenth impulse is impressed on the bank-'it-wilI cause the first trigger-pair to return to its-'oi'i condition with tube A non-conducting and tube A" conducting. Thereturn of the first pair to its off condition causes the second trigger pair to return to its oil? condition with tube B non-conducting and tube B conducting The return of the second -trigger-pair to its on. condition in turn causes the third trigger-pair to return ,to its 011 condition with 1 nomination.

condition further causes the fourth and final trigger-pair to return to its offfcondition With tube D non-conducting and tube D. conducting.

Since neither the third nor'the final trigger pair assumed an on condition in this entry, the second trigger pair remains in its 9 con- .ditiona'nd with allof the trigger pairs. in their on condition the bank has returned to its zero or starting condition.

. As the finaljtrigger pair returns to its "'ofi" conditioniand tuhe D becomes conducting, the

anode potential of tube D will drop and this ,drop can be, conveyed over conductor i5 as va transfer impulse to the next higher bank .or de- At the end of the entry. of the tenth impulse therefore, the tubes A, B, C, and]; will .be nonconducting, which is. the condition representativefof zero, and a transfer entry will have been madein the nexthigher denominational order. While (the form of mechanism herein shown and described is admirably adapted to fulfill the objects primarily stated, it is to be understood that itis not intended to confine the invention to the one form or embodiment herein disclosed, for it is susceptible of embodiment invarious forms all coming within the'scope of the claims which follow.

' Whatisclaimed is:

i1.. In combination, four electronic devices, each operable alternately to one and to another condition in response to impulses impressed thereon, and including means to produce potential changes each time the device changes from either condition to the other, said devices by their one and other conditions in combination representing the digits 1 to "9 and circuits connecting devices in series and enabling a potential change, produced by every second operati'on of one device, to be transmitted as an impulse to the next device of the series to cause an operation thereof; means to impress input impulses on the, first device'of the series; a unidirectional circuit connecting the third electronic device in the series to the smond electronic device in the series for transmitting a potential change, produced by the'third electronic device as it is operated to one of said conditions, as an impulse to the second electronic device to cause it-to operate; and a second uni-directional circuit connecting the fourth electronic device of the series to the second electronic device of the series for transmitting a potential change, produced by the fourth electronic device as it is operated to one of said conditions, as an impulse tothe second electronic device to cause itto operate; said series connections and two uni-directional connections cooperating. to enable the four electronic devices to operate to accumulate data in-the decimal notation by causing the electronic devices, in combinations, to progressively represent the digits 1 to 9 and 0 and to return to any particular digit representing combination after ten impulses have been applied to the input means.

2. In'combination, four pairs of electron discharge devices; circuits connecting each pair of devices to form a trigger-pair operable alternately to one and to another condition in response to impulses and including means to produce potential changes each time the pair changes from either condition to the other, said trigger-pairs; by combinations of said one and pair to transmit the potential change, produced.

by either the third or the fourth trigger pair assuming its one condition, as an impulse to the second trigger-pair to cause it to assume its one condition, said series connections and said fur-- ther connections cooperating to enable the four trigger-pairs to accumulate data ina decimal guesses iii notation by being caused to be in said one and said other conditions, in combinations, to represent digits 1 to 9 and 0 and by returning to any particular combination. after ten impulses have been applied to the input means.

3. In combination, four pairs of electron tubes; circuits connecting each pair of tubes to form a trigger-pair operable alternately to an on and to an ofi condition in response to impulses and including means to produce potential changes each time the pair changes from either condition to the other, said trigger-pairs by combinations of on and off conditions representing the digits 1 to 9 and 0; circuits connecting the trigger-pairs in series to transmit the potential change, produced by the turning of a trigger-pair to its off condition, as an impulse to the next trigger-pair of the series to cause it to operate and change its on or off condition; an input circuit upon which input impulses are applied tothe first trigger-pair of the series to cause it to operate alternately to its on and its ofi conditions; and further circuits connecting the third and. fourth trigger-pairs in the series to the second trigger-pair to transmit the potential change, produced by the turning of either the third or the fourth trigger-pair to its on condition, as an impulse to the second trigger-pair to cause it to operate and assume its on condition, said series connections and said further connections cooperating to enable the four trigger-pairs to accumulate data in a decimal notation by being turned on and off in combinations to represent digits 1 to 9 and 0 and by returning to any particular combination after ten impulses have been applied to the input means. g

4. In combination, four pairs of high-vacuum electron tubes; circuits connecting each pair of tubes to form a trigger-pair operable alternately to an on and to an off condition in response to impulses and including means to produce potential changes each time the pair changes from either condition to the other, said trigger-pairs by combinations of on and off conditions representing the digits 1 to 9 and 0; circuits connecting the trigger-pairs in series to transmit the potential change, produced by the turning of a trigger-pair to its off condition, as an impulse to the next trigger pair of the series to cause it to operate and change its on or "011? condition; an input circuit upon which input impulses are applied to the first triggerpair of the series to cause it to operate alter- .nately to its on and to its off conditions; a

uni-directional circuit connecting the third trigger-pair in the series to the second trigger-pair to transmit the potential change, produced .by the turning of the third trigger pair to its on condition, as an impulse to the second triggerpair to cause it to operate to its on condition; and a second uni-directional circuit connecting the fourth trigger-pair in the series to the second trigger-pair to transmit the potential change, produced by the turning of the fourth triggerpair to its on condition, as an impulse to the second trigger-pair to cause it to operate to its on condition; said series connections and two uni-directional connections cooperating to enable the four trigger-pairs to accumulate data in the decimal notation by causing the triggerpairs, in combination, to progressively represent the digits 1 to 9 and 0 and to return to any particular combination after ten impulses have been applied to the input means.

5, In a four denominational binary counter adapted for decimal counting, the combination of means for indicating a value of 2 in response to entries therein; means for indicating a value of 2 in response to entries therein; means for indicating a value of 2 in response to entries therein; means for indicating a value of 2 in response to entries therein; means to apply input irnpulses to the meansfor indicating a value of 2 to enter values into the counter; transfer 1 means between the several indicating means to cause a unit entry to be made into a higher order for each twonnitentries in the next lower order; means controlled by the means for indicating a value of 2 as the means indicates this value, for causing an entry to be made in the means for indicating a value of 2 and means controlled by the means for indicating a value causing an entry to be made in the means 'for indicating a value of '2 said means controlled by the means for indicating a value of 2 causing two entries to-be made in the means for indicating a value of 2 and said means controlled by the means for indicating a value of 2 causing one entry to be made in the means for indicating a value of 2 during the entry of each ten impulses in the counter, thereby automatically to add a value of six in the counter. and enable the counter to make a complete operation and return to starting condition upon the application of ten impulses thereto.

6. .In an apparatus for accumulatin values in the decimal notation, the combination of four pairs of electron discharge devices, each of said devices containing at least an anode, a cathode, and means to control conduction therebetween; circuits for applying operating potentials to the devices and includinga separate impedance element in the circuit to each anode; trigger connections cross-connecting the anodes and the conduction control means of the devices of each pair so that the pair will operate in on condition when current is conducted in one of the devices and in oil condition when current is conducted in the other of the devices, the trig er pairs, by combinations of on and off conditions, representing the digits 0,,and 1 to"9; circuits connecting the trigger-pairs in cascade, the cascade circuits between trigger pairs extending from the anode of saidlother device of a pair to the conduction control means of both devices of the next pair of the cascade,.for transmitting the anode potential drop, as the trigger pair'turns to its ofi condition, to the next trigger pair to cause an operationthereof; means to preset the trigger pairs to'theirfofi condition;

.of- 2. as the means indicates this value, for

.to the second pair to turn it from off to on;

and a second unidirectional circuit extending from the anode of the one device or the fourth trigger pair directly to the conduction control means of the other device of the second trigger pair to transmit the potential change, which is produced when the fourth trigger pair is turned on, as an impulse to the second trigger pair to cause it to operate from off to on condition; said series connections and two unidirectional connections cooperating to enable the four trigger pairs to accumulate data in the decimal notationby causing the second trigger-pair to make three additional operations during one cycle of operation of the devices whereby the trigger pairs, in combination, can operate cyclically to progressively represent the digits 1" to 9 and 0 and return to any particular combination after ten impulses have caused a cycle of operation thereof.

ROBERT E. MUMMA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,310,105 Michel Feb. 2, 1943 2,402,432 Mumma June 18, 1946 2,402,988 Dickinson July 2, 1946 2,402,989 Dickinson July 2, 1946 2,404,918 Overbeck July 30, 1946 2,436,963 Grosdofi Mar. 2, 1948 2,521,788 Grosdofi Sept. 12, 1950 2,538,122 Potter Jan. 16, 1951 2,552,781 .Hadfield Ma 15, 1951 OTHER REFERENCES Electronic Industries, July 1945, T. H. John son, page 84.

Electronic Counters, by I. E. Grosdofi, pages 441-443. Reprinted from RCA Review, September 1946, vol. VII, No. 13.

Electronic Industries-for July, 1945, pages 97 to 99, 130, 184, 138, 142 and 146.

Electronics for June, 1944, pages 110 to 113, 358 and 360. 

